* - A setter `setX` of an upgraded property is removed
     * - A boolean `isX` of an upgraded property is removed
     * - A new getter `getX` is added, where the old getter is a boolean getter `isX` of an upgraded property
     * - A return type is changed for a getter `getX` of an upgraded property
     *
     * We don't automatically accept changes when the @since annotation is missing, because we want to keep this information on the API.

 * their lifecycle is shared as well: once supplied repository system is shut-down, this instance becomes closed as
 * well. Any subsequent {@code getXXX} method invocation attempt will fail with {@link IllegalStateException}.
 */
public class RepositorySystemSupplier implements Supplier<RepositorySystem> {
    private final AtomicBoolean closed = new AtomicBoolean(false);